Flexible pipe and conduit structures are used in a variety of applications. For example, vehicular exhaust systems make use of flexible conduits in order to accommodate the jarring, vibration and thermal stresses to which the exhaust system is subjected when the vehicle is in use. Examples of spiral wound flexible pipes suitable for use in vehicular exhaust systems are disclosed in U.S. Pat. No. 6,497,254 to Thomas et al. Bellows type systems which provide flexibility by using corrugated conduits are exemplified by U.S. Pat. No. 7,066,495 to Thomas et al. The latter patent also discloses an arrangement for interfitting the corrugations on the pipes in a manner to allow relative rotation at the pipe joints.
These prior art exhaust systems function in a generally satisfactory manner for the most part. The flexibility of the pipes allows them to withstand the forces that are applied due to jolts, vibrations and thermal stresses. The rotary or torsional joint is especially beneficial in many applications because it is able to accommodate torsional loading without unduly stressing the pipes. Even so, the prior art exhaust systems of this type have not been completely free of problems.
In particular, the vibration and other movement creates substantial noise which can be aggravated by the hot exhaust gases going through the pipes. Additionally, the heat from the exhaust gases causes the outside surfaces of the pipes to reach temperatures that can be high enough to create undue heat stress on the piping and safety hazards if contacted by persons. These noise and heat problems have not been successfully addressed and have been increasing causes for concern due to the increasing emphasis that has been placed on controlling noise pollution and increasing concern with safety considerations.